Organic molecules hydrogenolysis

Hydrocracking. Hydrogenolysis of a carbon—carbon bond in an organic molecule produces smaller, hydrogen-saturated molecules and is termed hydrocracking when 50% or more of the feedstock is converted into smaller molecules. 

Thiophene metal poisoning as well as hydrogenation of ethylbenzene on metal catalysts require, as a first step, the chemisorption of both organic molecules on the metal active sites. Afterwards, catalyst deactivation can simply take place by the blocking of these sites or by further hydrogenolysis of thiophene and subsequent formation of an inactive surface metal sulfide. We believe that, in our conditions, this last mechanism is probably operating. This hypothesis is supported by the fact that butane was detected in our experiments and, furthermore, XPS analysis showed the formation of metal sulfides (S ) on the deactivated catalysts. 

In this section we discuss INS studies of metal catalysts where the main interest is the hydrogenation or hydrogenolysis of a hydrocarbon or other organic molecule. Such metal catalysts have at least two functions to split the H2 molecule providing reactive H atoms and to bind and activate a reactant molecule. In some cases hydrogen atoms may spillover from the catalyst to a support establishing a reservoir of... 

Hydrogenolysis. In the removal of halogen from an organic molecule by hydro-genolysis, the hydrogen halide formed poisons the catalyst unless neutralized. Reinecke25 found that triethylamine can be used and is sometimes superior to sodium... 

The classical treatment of Langmuir kinetics on uniform surfaces can be extended to the reactions that occur on two types of sites in close proximity. The reaction proceeds via interactions between species adsorbed on such distinct sites. Examples of such reactions are various oxidation reactions on metal oxides, which contain two types of sites, metal atoms sites and oxygen atom sites, each having a specific function. Another example is hydrogenolysis of haloarenes where spillover hydrogen reacts with an organic molecule adsorbed on the metal surface ... 

An interesting study of the products of cubane hydrogenolysis was published by Stober, Musso and Osawa (39). In this reaction the authors found [2.2.2]bicyclooctane (83) to be the main product tetracyclo[4.2.0.0 .0 ]-octane (84) and tricyclo[4.2.0.0 ]octane (85) were identified as intermediates. The experimental findings have been rationalized by means of MM study of possible products of the reaction. It should be stressed that MM is mainly used to determine spatial structure and strain of organic molecules, and the method is seldom applied to explain the reactivity and course of reactions as has been done by the Osawa group. 

Halides are common components of organic molecules, and in many cases they must be removed. One way to do this is reduction to the corresponding hydrocarbon by hydrogenolysis. A nickel catalyst (usually... 

Catalytic hydrogenolysis is the cleavage of a molecule into fragments by hydrogen in the presence of a catalyst It is a useful and frequent synthetic reaction. This chapter is organized around the type of bond being cleaved. 

Poly(propylene imine) (PPI or POPAM) dendrimers are the first dendritic stmctures found in literature. They were first reported by Buhleier etal, who presented a divergent synthesis of branched and dendritic-like molecules. These simple structures were accomplished using controlled organic chemistry. In this case, a Michael reaction between a primary amine and two equivalents of acrylonitrile resulted in a dinitrile. Further reduction through Co(II)-catalyzed hydrogenolysis led to a terminal diamine (Figure 16). An iterative protocol allowed the con-stmction of what today is defined as a second-generation... 

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